Who is right in this situation?

My aunt owned a profitable beauty salon in Central Machusetts that a coworker agreed to purchase. As part of the purchase contract my aunt agreed not to compete in a personal service business anywhere in Machusetts for 2 years. Eighteen months later, my aunt opened a beauty salon in Boston. When the coworker found out she sued my aunt claiming my aunt violated her covenant not to compete. My aunt defended by claiming that the agreement should not be enforced because it violates public policy. Who is correct here?